First part:
-Go to emergency call
-Dial 112 (or 911?) and tap green and red INMEDIATELY, INSTANTLY.
-Go to lock screen.
Ok...ready for second part:
-Go to passcode screen.
-Keep pushing down the power button ...1...2...3...(+0.5?) seconds and before showing the slider "turn off"...tap the emergency call button and ...voilá!
-Then without releasing the power button press the home button (screen shot) and ready...